Self-expandable metal stents and trans-stent light delivery: are metal stents and photodynamic therapy compatible?
OBJECTIVE
Obstructive non-small cell lung cancer and obstructive esophageal cancer are US FDA approved indications of photodynamic therapy (PDT). The usefulness of PDT for the treatment of cholangiocarcinoma is currently under clinical investigation. Endoscopic stenting for lumen restoration is a common palliative intervention for those indications. It is important to assess whether self-expandable metal stents are compatible with trans-stent PDT light delivery.


METHODS
Direct effects of various components of metal biliary (n = 2), esophageal (n = 2), and bronchial (n = 1) stents on PDT light transmittance and distribution were examined using a point or linear light source (630 or 652 nm diode laser). Resected pig biliary duct and esophageal wall tissues were used to examine the feasibility of PDT light delivery through the fully expanded metal stents.


RESULTS
While using a point light source, the metal components (thread and joint) of the stent could cause a significant shadow effect. The liner material (polytetrafluoroethylene or polyurethane) could cause various degrees of light absorption. When the stent was covered with a thin layer of biliary duct and esophageal tissues containing all wall layers, the shadow effect could be mitigated due to tissue scattering.


CONCLUSIONS
This study clearly demonstrates that it is feasible to combine stenting and PDT for the treatment of luminal lesions. PDT light dose should be adjusted to counteract the reduction of light transmittance caused by the metal and liner materials of stent.
Wang
Luo-Wei
LW
Department of Gastroenterology, Changhai Hospital, Shanghai, PR China.
Li
Li-Bo
LB
Li
Zhao-Shen
ZS
Chen
Yang K
YK
Hetzel
Fred W
FW
Huang
Zheng
Z
D000497:Alloys; D000818:Animals; D001652:Bile Ducts; D000075202:Contraindications; D004867:Equipment Design; D004947:Esophagus; D008422:Materials Testing; D055620:Optical Phenomena; D010778:Photochemotherapy; D011138:Polytetrafluoroethylene; D011140:Polyurethanes; D013193:Stainless Steel; D015607:Stents; D013552:Swine; D046509:Tissue Culture Techniques
D000497:Alloys; D011140:Polyurethanes; D013193:Stainless Steel; C013616:nitinol; D011138:Polytetrafluoroethylene